Poly

public protocol Poly

Poly is a protocol to which types that are polymorphic belong to.

Specifically, Poly1, Poly2, Poly3, etc. types conform to the Poly protocol. These types allow typesafe grouping of a number of disparate types under one roof.

Access

You can access the value of a Poly type in one of four different ways.

1. You can switch over its cases

   switch poly2Value {
   case .a(let value):
       // value is of type `A`
   case .b(let value):
       // value is of type `B`
   }
   

2. You can ask for a value by accessor

   let value1 = poly2Value.a // value1 is of type `A?`
   let value2 = poly2Value.b // value2 is of type `B?`
   

3. You can ask for a value by type

   let value1 = poly2Value[A.self] // value1 is of type `A?`
   let value2 = poly2Value[B.self] // value2 is of type `B?`
   

4. You can ask for a type-erased value

   let value = poly2Value.value // value is of type `Any`